High-resolution beamline 9.3.2 in the energy range 30-1500 eV at the advanced light source: Design and performance

Bending magnet beamline 9.3.2 at the Advanced Light Source (ALS) was designed for high resolution spectroscopy with capability for delivering circularly polarized light in the soft X-ray energy region using three gratings. The monochromator is a fixed included angle spherical grating monochromator (SGM) and was originally used at SSRL as a prototype for later insertion device based monochromators for the ALS, For operation at the ALS, the toroidal pre-mirror used at SSRL was replaced by a horizontally focusing and a vertically focusing mirrors in the Kirkpatrick-Baez configuration. Circularly polarized radiation is obtained by inserting a water-cooled movable aperture in front of the vertically focusing mirror to allow selecting the beam either above or below the horizontal plane. To maintain a stable beam intensity through the entrance slit, the photocurrent signals from the upper and lower jaws of the entrance slit are utilized to set a feedback loop with the vertically deflecting mirror piezoelectric drive. The beamline end station has a movable platform that accommodates two experimental chambers enabling the synchrotron radiation to be directed to either one of the two experimental chambers without breaking the vacuum